The present invention is directed generally to a row follower guidance apparatus for a tractor and more specifically to a laterally adjustable centerline sight including a reverse pendulum.
In the past, a tractor operator generally used the center crease in the hood of the tractor as the sight for maintaining the tractor in its properly centered position relative to crop rows. It has been found, however, that there is a significant variation in the positioning of a tractor by different operators because some people are right-eye-dominated and others are left-eye-dominated. The dominant eye is that used for establishing a single line of sight. Most operators align the tractor hood crease or ornament with the guide furrow for centering the tractor but the lines of sight of a left-eye-dominated operator and a right-eye-dominated operator will result in substantially different positions of the tractor relative to the guide furrow.
To resolve this problem, the present inventor developed the furrow follower vision correction system described in U.S. Pat. No. 4,401,166. That system includes a laterally adjustable tractor sighting device which can be adjusted by various operators to accomodate their particular positioning on the tractor seat and dominant eye. Thus by simple lateral adjustment of the sighting device, all operators can easily maintain a uniform and centered position of the tractor relative to planted rows of crops or any other visible centerline.
Whereas the device of U.S. Pat. No. 4,401,166 is believed to be a significant advance in the art, a problem is encountered with the use of this device on hilly terrain. Even on hills, the sighting device is affected only slightly, if at all, by the tractor driving directly up or down a sloping surface. The problem occurs when the tractor drives transversely across the side of a hill whereupon the wheels on one side of the tractor are elevated above the wheels on the opposite side of the tractor. This canting of the tractor toward the downhill direction causes the operator's line of sight through the laterally adjusted sighting device to be offset from the centerline being followed by the tractor. This problem is believed to be resolved by the centerline sight of the present invention which is equipped with a reverse pendulum.
Maier U.S. Pat. No. 2,538,112 shows a sighting device with a straight pendulum without the reverse gearing of the present invention. Such a device is believed to exaggerate the problem rather than solve it since the sight is laterally moved in the wrong direction in response to lateral tilting of the tractor.
Accordingly, a primary object of the present invention is to provide an improved centerline sight for a tractor.
Another object is to provide a centerline sight for a tractor which is laterally adjustable to compensate for the various driving positions and dominant eyes of various operators.
Another object is to provide such a laterally adjustable centerline sight which is equipped with a reverse pendulum so that a proper line of sight is maintained when the tractor is laterally tilted.
Another specific object is to provide a centerline sight wherein the sighting needle is offset in the same direction as the pendulum weight in response to lateral tilting of the tractor.
Finally, another object is to provide a laterally adjustable centerline sight with reverse pendulum which is simple and rugged in construction, inexpensive to manufacture and efficient in operation.